Customized lenses

ABSTRACT

The invention relates to a method of customizing lenses using an external stimulus such as light. Fine-tuning of the lens to match the precise optical requirements using the same lens is also possible. The lenses are self-contained and do not require the addition or removal of significant portions of the lens to achieve customization.

[0001] This Invention is claiming priority to the U.S. ProvisionalPatent Application No. 60/344,248 on said Invention filed on Dec. 28,2001.

BRIEF SUMMARY OF THE INVENTION

[0002] The present invention is directed to customized lenses and amethod for making them. In one embodiment, lenses are provided whoseoptical properties can be customized through the use of external stimulisuch as light or other radiation.

BACKGROUND OF THE INVENTION

[0003] The most common method for correcting vision is through the useof corrective lenses, e.g., spectacles, contact lenses, and intraocularlenses. In the case of each of these lenses, the lenses areprefabricated with a specific set of optical properties, mostly opticalpower.

[0004] In some cases, the lenses are capable of some post-fabricationmodification (e.g., grinding of lenses). In many cases, the lenses mustbe prefabricated to a specific power or diopter. In still otherinstances, the desired optical properties must be estimated and thelenses specifically fabricated. The latter process can be time-consumingand inexact.

[0005] The typical solution to this problem has been the maintenance ofan inventory of lenses with a wide assortment of optical powers. Forexample, an optometrist often maintains a large inventory of contactlenses having different diopter values so that prescriptions can bequickly filled. When a lens is out of stock or when a patient requires acustom lens, special orders must be made, causing delays in dispensingthe lens.

[0006] Thus, there exists a need for lenses which can be readilycustomized to fit the patient's needs. In this manner, precisecorrection of the patient's vision can be performed without significantdelay or expense.

[0007] The foregoing has outlined rather broadly the features andtechnical advantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the invention as set forth in the appendedclaims. The novel features which are believed to be characteristic ofthe invention, both as to its organization and method of operation,together with further objects and advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

SUMMARY OF THE INVENTION

[0008] Customizable lenses are provided whose optical properties can beadjusted post-manufacture without the addition or removal of materialfrom the lens. The lenses are self-contained units having dispersedtherein a modifying composition (“MC”) which, when exposed to anexternal stimulus, changes the optical properties of the lens.

[0009] As used herein, the term “self-contained” means that the lensesare self supporting and contain all the elements necessary to affect thechange in optical properties without the addition or removal ofmodifying compositions. For example, in the preferred embodiment, thelenses comprise a fully or partially cross-linked polymer matrix havingMCs dispersed throughout the matrix. Only the exposure of a portion ofthe MC to an external stimulus followed by the polymerization of the MCwithin the matrix in the said portion is required to affect the changesin optical properties. No modifying composition is added or removed fromthe lens to induce the change in properties.

[0010] A method for preparing customized lenses is also provided. In themethod, the correction requirements of the patient is determined. A lenscontaining a modifying composition is selected. The lens is then exposedto an external stimulus in a manner that the optical properties of thelens are changed so as to provide the desired vision correction. Thelenses are then dispensed to the patient. Adjustments can be madewithout adding or removing modifying composition.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Corrective lenses are provided which can be customized,post-manufacture, to suit the specific needs of the user. The opticalproperties of the lenses can be modified without the addition or removalof materials from the lens.

[0012] The lenses contain a MC dispersed throughout the lens. The MC iscapable of stimulus-induced polymerization and can freely diffuse ormigrate within the lens.

[0013] In one embodiment, the lens is formed from a first polymer matrixwhich has the MC dispersed throughout. The first polymer matrix givesthe lens its basic shape as well as its physical properties, such ashardness, clarity, flexibility and the like.

[0014] The nature of the first polymer matrix and the MC will varydepending upon the end use contemplated for the optical element.However, as a general rule, the first polymer matrix and the MC areselected such that the components that comprise the MC are capable ofdiffusion within the first polymer matrix. Put another way, a loosefirst polymer matrix will tend to be paired with larger MC componentsand a tight first polymer matrix will tend to be paired with smaller MCcomponents. While the FPM generally comprises a crosslinked matrix, theFPM need not be fully crosslinked, but may be partially crosslinked. Theonly requirement is that the FPM be self suupportive and allow thediffusion of the MC within the FPM and allow the crosslinking of MC uponexposure to the appropriate stimulus.

[0015] Upon exposure to an appropriate energy (e.g., heat or light), theMC typically forms a second polymer matrix in the exposed region of theoptical element. The presence of the second polymer matrix changes thematerial characteristics of this portion of the optical element tomodulate its refraction capabilities. In general, the formation of thesecond polymer matrix typically increases the refractive index of theaffected portion of the optical element. After exposure, the MC in theunexposed region will migrate into the exposed region over time. Theamount of MC migration into the exposed region is time dependent and maybe precisely controlled. If enough time is permitted, the MC componentswill re-equilibrate and redistribute throughout optical element (i.e.,the first polymer matrix, including the exposed region). When the regionis re-exposed to the energy source, the MC that has since migrated intothe region (which may be less than if the MC were allowed tore-equilibrate) polymerizes to further increase the formation of thesecond polymer matrix. This process (exposure followed by an appropriatetime interval to allow for diffusion) may be repeated until the exposedregion of the optical element has reached the desired property (e.g.,power, refractive index, or shape).

[0016] The first polymer matrix is a covalently or physically linkedstructure that functions as an optical element and is formed from afirst polymer matrix composition (“FPMC”). In general, the first polymermatrix composition comprises one or more monomers that uponpolymerization will form the first polymer matrix. The first polymermatrix composition optionally may include any number of formulationauxiliaries that modulate the polymerization reaction or improve anyproperty of the optical element. Illustrative examples of suitable FPMCmonomers include acrylics, methacrylates, phosphazenes, siloxanes,vinyls, homopolymers and copolymers thereof. As used herein, a “monomer”refers to any unit (which may itself either be a homopolymer orcopolymer) which may be linked together to form a polymer containingrepeating units of the same. If the FPMC monomer is a copolymer, it maybe comprised of the same type of monomers (e.g., two differentsiloxanes) or it may be comprised of different types of monomers (e.g.,a siloxane and an acrylic).

[0017] In one embodiment, the one or more monomers that form the firstpolymer matrix are polymerized and cross-linked in the presence of theMC. In another embodiment, polymeric starting material that forms thefirst polymer matrix is cross-linked in the presence of the MC. Undereither scenario, the MC components must be compatible with and notappreciably interfere with the formation of the first polymer matrix.Similarly, the formation of the second polymer matrix should also becompatible with the existing first polymer matrix. Put another way, thefirst polymer matrix and the second polymer matrix should not phaseseparate and light transmission by the optical element should beunaffected.

[0018] As described previously, the MC may be a single component ormultiple components so long as: (i) it is compatible with the formationof the first polymer matrix; (ii) it remains capable of stimulus-inducedpolymerization after the formation of the first polymer matrix: and(iii) it is freely diffusable within the first polymer matrix. Inpreferred embodiments, the stimulus-induced polymerization isphotoinduced polymerization.

[0019] The inventive lenses comprises a first polymer matrix and a MCdispersed therein. The first polymer matrix and the MC are as describedabove with the additional requirement that the resulting lens bebiocompatible.

[0020] Illustrative examples of a suitable first polymer matrix include:polyacrylates such as polyalkyl acrylates and polyhydroxyalkylacrylates; polymethacrylates such as polymethyl methacrylate (“PMMA”), apolyhydroxyethyl methacrylate (“PHEMA”), and polyhydroxypropylmethacrylate (“HPMA”); polyvinyls such as polystyrene andpolyvinylpyrrolidone (“NVP”); polyvinyl alcohols with polymerizable endgroups such as methacrylate side groups; polysiloxanes such aspolydimethylsiloxane; polyphosphazenes, and copolymers thereof. U.S.Pat. No. 4,260,725 and patents and references cited therein (which areall incorporated herein by reference) provide more specific examples ofsuitable polymers that may be used to form the first polymer matrix.

[0021] In embodiments where flexibility is desired (e.g., contactlenses), the first polymer matrix generally possesses a relatively lowglass transition temperature (“T_(g)”) such that the resulting lenstends to exhibit fluid-like and/or elastomeric behavior, and istypically formed by cross-linking one or more polymeric startingmaterials wherein each polymeric starting material includes at least onecross-linkable group. In other embodiments, flexibility is lessimportant (e.g., spectacle lenses). In this case, the monomers are suchthat the finished lens has a T_(g) of >25° C. In another embodiment, theFPM and MC are dissolved in a suitable medium. The solution is thenexposed to an external stimulus causing the crosslinking of the FPM andsome of the MC to form a self supporting structure being MC dispersedtherein. The optical properties of the lens are then modified by there-exposing the lens to the external stimulus. This causes furtherpolymizeration of the full MC and inducing changes in the lens withmanner described above. Alternatively, if the MC has already beencrosslinked, if there are additional reactive groups present, furthercrosslinking can occur inducing additional changes in opticalproperties.

[0022] Illustrative examples of suitable cross-linkable groups includebut are not limited to hydride, acrylate, methacrylate, acetoxy, alkoxy,amino, anhydride, aryloxy, carboxy, enoxy, epoxy, halide, isocyano,olefinic, and oxine. In one preferred embodiments, each polymericstarting material includes terminal monomers (also referred to asendcaps) that are either the same or different from the one or moremonomers that comprise the polymeric starting materials but include atleast one cross-linkable group. In other words, the terminal monomersbegin and end the polymeric starting material and include at least onecross-linkable group as part of their structure. In second preferredemodiments, each polymeric starting material has crosslinkable groupspresent either at the terminal ends or side groups or both which cancrosslink to form the network (e.g. CIBA's patents—crosslinking occursvia the reactive side grouips along the polymer backbone. In onepreferred embodiment, the mechanism for cross-linking the polymericstarting material preferably is different than the mechanism for thestimulus-induced polymerization of the components that comprise the MC.For example, if the MC is polymerized by photoinduced polymerization,then it is preferred that the polymeric starting materials havecross-linkable groups that are polymerized by any mechanism other thanphotoinduced polymerization.

[0023] In an alternative embodiment, the polymerization mechanism forthe MC and the starting materials for the first polymer matrix can bethe same, but the rates of polymerization must be different such thatthe first polymer matrix is substantially complete before significantamounts of MC have been polymerized. For example, wherephotopolymerization is used to form the first polymer matrix and topolymerize the MC, the starting material for the first polymer matrixmay contain reactive methacrylate groups as the polymerizable moietywhereras the MC may contain reactive acrylate groups. These groupsphotopolymerize at significantly different rates allowing the formationof the first polymer matrix before significant amounts of the MC havepolymerized.

[0024] An especially preferred class of polymeric starting materials forthe formation of the first polymer matrix is polysiloxanes (also knownas “silicones”) endcapped with a terminal monomer which includes across-linkable group selected from the group consisting of acetoxy,amino, alkoxy, halide, hydroxy, and mercapto. Because silicone IOLS tendto be flexible and foldable, generally smaller incisions may be usedduring the IOL implantation procedure. An example of an especiallypreferred polymeric starting material isbis(diacetoxymethylsilyl)-polydimethysiloxane (which ispolydimethylsiloxane that is endcapped with a diacetoxymethylsilylterminal monomer).

[0025] Another class of materials that may be useful in forming thelenses of the invention are acetal derivatives of polyvinyl alcoholsPVAs having crosslinkable end groups such as methacrylate groups alongthe backbone of the PVA. Illustrative examples of such materials aredescribed in U.S. Pat. No. 5,508,317, the teachings of which areincorporated by reference. The derivatized PVA should have a molecularweight of at least 10,000.

[0026] Still another class of materials that may be useful in thepractice of the invention are polyhydroxymethacrylates (poly(HEMA))having polymerizable groups such as those described in U.S. Pat. Nos.4,495,313 and 4,680,336, the teachings of which are hereby incorporatedby reference. The (poly(HEMA)s) should have a molecular weight of atleast 10,000.

[0027] The MC that is used in fabricating IOLs is as described aboveexcept that it has the additional requirement of biocompatibility. TheMC is capable of stimulus-induced polymerization and may be a singlecomponent or multiple components so long as: (i) it is compatible withthe formation of the first polymer matrix; (ii) it remains dispersed inthe FPM and is capable of stimulus-induced polymerization after theformation of the first polymer matrix; and (iii) it is freely diffusablewithin the first polymer matrix. In general, the same type of monomersthat are used to form the first polymer matrix may be used as componentsof the MC. However, because of the requirement that the MC monomers mustbe diffusable within the first polymer matrix, the MC monomers generallytend to be smaller (i.e., have lower molecular weights) than themonomers which form the first polymer matrix. In addition to the one ormore monomers, the MC may include other components such as initiatorsand sensitizers that facilitate the formation of the second polymermatrix.

[0028] Because of the preference for flexible and foldable IOLs andflexible contact lenses, an especially preferred class of MC monomers ispolysiloxanes endcapped with a terminal siloxane moiety that includes aphotopolymerizable group. An illustrative representation of such amonomer is:

X—Y—X¹

[0029] wherein Y is a siloxane which may be a monomer, a homopolymer ora copolymer formed from any number of siloxane units, and X and X¹ maybe the same or different and each contain a moiety that includes aphotopolymerizable group. Illustrative examples of Y include:

[0030] wherein: m and n are independently each an integer and R¹, R²,R³, and R⁴, are independently each hydrogen, alkyl (primary, secondary,tertiary, cyclo), aryl, or heteroaryl. In preferred embodiments, R¹, R²,R³, and R⁴, is a C_(l)-C₁₀ alkyl or phenyl. Because MC monomers with arelatively high aryl content have been found to produce larger changesin the refractive index of the inventive lens, it is generally preferredthat at least one of R¹, R², R³, and R⁴ is an aryl, particularly phenyl.In more preferred embodiments. R¹, R², R³ are the same and are methyl,ethyl or propyl and R⁴ is phenyl.

[0031] Illustrative examples of X and X¹ (or X¹ and X depending on howthe MC polymer is depicted) are

[0032] respectively wherein:

[0033] R⁵ and R⁶ are independently each hydrogen, alkyl, aryl, orheteroaryl; and

[0034] Z is a photopolymerizable group.

[0035] In preferred embodiments R¹ and R⁶ are independently each a C₁and C₁₀ alkyl or phenyl and Z is a photopolymerizable group thatincludes a moiety selected from the group consisting of acrylate,allyloxy, cinnamoyl, methacrylate, stibenyl, and vinyl. In morepreferred embodiments, R⁵ and R⁶ is methyl, ethyl, or propyl and Z is aphotopolymerizable group that includes an acrylate or methacrylatemoiety.

[0036] In addition to the silicone-based MCs described above,acrylate-based MC can also be used in the practice of the invention. Theacrylate-based macromers of the invention have the general structure

X-A_(n)-Q-A_(n)-X¹

[0037] or

X-A_(n)-A¹ _(m)-Q-A¹ _(m)-A_(n)-X¹

[0038] wherein Q is an acrylate moiety capable of acting as an initiatorfor Atom Transfer Radical Polymerization (“ATRP”), A and A¹ have thegeneral structure:

[0039] wherein R⁷ is selected from the group comprising alkyls,halogenated alkyls, aryls and halogenated aryls, and R⁸ equals H, CH₃,alkyl, and fluoroalkyl, and X and X¹ are groups containingphotopolymerizable moieties and m and n are integers.

[0040] In one embodiment the acrylate based MC has the formula

[0041] wherein R⁹ is selected from the group comprising alkyls andhalogenated alkyls R¹⁰ and R¹¹ are different and are selected from thegroup consisting of alkyls, halogenated alkyls, aryls and halogenatedaryls, x and x¹ are as defined above and is either zero or an interger.

[0042] In especially preferred embodiments, an MC monomer is of thefollowing formula:

[0043] wherein x and x¹ are the same and R¹, R², R³, and R⁴ are asdefined previously. Illustrative examples of such MC monomers includedimethylsiloxane-diphenylsiloxane copolymer endcapped with a vinyldimethylsilane group; dimethylsiloxane-methylphenylsiloxane copolymerendcapped with a methacryloxypropyl dimethylsilane group; anddimethylsiloxane endcapped with a methacryloxypropyldimethylsilanegroup. Although any suitable method may be used, a ring-opening reactionof one of more cyclic siloxanes in the presence of triflic acid has beenfound to be a particularly efficient method of making one class ofinventive MC monomers. Briefly, the method comprises contacting a cyclicsiloxane with a compound of the formula:

[0044] in the presence of triflic acid wherein R⁵, R⁶, and Z are asdefined previously. The cyclic siloxane may be a cyclic siloxanemonomer, homopolymer, or copolymer. Alternatively, more than one cyclicsiloxane may be used. For example, a cyclic dimethylsiloxane tetramerand a cyclic methyl-phenylsiloxane trimer are contacted withbismethacryloxypropyltetramethyldisiloxane in the presence of triflicacid to form a dimethyl-siloxane methyl-phenylsiloxane copolymer that isendcapped with a methacryloxylpropyl-dimethylsilane group, an especiallypreferred MC monomer.

[0045] In another embodiment, where the first polymer matrix is formedfrom derivatized PVAs of from (poly(HEMA)s with reactive groups, the MCmay be formed from the same compositions, but with significantly lowermolecular weights (i.e. ˜1,000) and with reactive groups whichpolymerize via a different mechanism, or at a substantially differentrate. In one embodiment, the first polymer matrix is formed by thephotopolymerization of an acetal derivatized PVA having reactivemethacrylate side groups. The derivaized PVA has a molecular weight ofabout 10,000. In this case, the MC may comprise a similar derivatizedPVA with a lower molecular weight (˜1,000) and having reactive acrylateside groups. Upon exposure to photoradiation, the higher molecularweight derivatized PVA will polymerize faster than the MC forming thepolymer matrix before significant amounts of the MC have beenpolymerized. This creates a polymer matrix with free MC dispersedtherein. The free MC is then available for further polymerization aspart of the customization process. Similar results may be achieved usinghigh and low molecular weight (poly(HEMA)s with different polymerizableside groups.

[0046] As discussed above, the stimulus-induced polymerization requiresthe presence of an initiator. The initiator is such that upon exposureto a specific stimuli, it induces or initiates the polymerization of theMC. In the preferred embodiment, the initiator is a photoinitiator. Thephotoinitiator may also be associated with a sensitizer. Examples ofphotoinitiators suitable for use in the practice of the invention areacetophenones (e.g., substituted haloaceto phenones anddiethoxyacetophenone); 2,4-dichloromethyl-1,3,5-triazines; benzoinmethyl ether; and O-benzoyl oximino ketone.

[0047] Suitable sensitizers include p-(dialkylamino aldehyde);n-alkylindolylidene; and bis [p-(dialkyl amino) benzylidene] ketone.

[0048] In practice of the invention, lenses are prefabricated in themanner described above. These lenses are then modified based on thepatient's specific needs in the following manner.

[0049] First, the patient is examined to determine the individual'sspecific optical needs. This examination is the same as routinelyconducted by ophthalmologists and optometrists. It may involveautorefraction, wavefront based aberrometric analysis, surfacetopography, and the like.

[0050] Based on the results of the examination, a prescription isdeveloped, specifying the desired properties for the lenses. This caninclude correction for myopia, astigmatism and the like. Once thesecorrection values have been determined, an unmodified lens is thenexposed to an external stimulus in a pattern and at sufficient intensityto induce the desired changes in the lenses. Once the desired propertieshave been achieved, the lenses are dispersed to the patient.

[0051] The lens is modified by exposing the lens to an external stimulusin a pattern to modify the optical properties of the lens to correct thevision of the patient. This is accomplished by either altering therefraction index of the lens or by changes in the shape of the lens, orboth. In the preferred embodiment, the change in refraction is caused bypolymerization of MC in at least a portion of the lens coupled withmigration of unpolymerized MC within the lens to reestablish a uniformconcentration of MC throughout the lens. Polymerization of the MC causesthe creation of a second polymer matrix in the exposed region. Thissecond polymer matrix causes a change in the optical properties of thelens in the exposed region. The migration of unpolymerized MC causesswelling of the lens in the exposed region. This in turn alters theshape of the element, again changing the optical properties. When the UVsource is removed, the unpolymerized MC in the unexposed lens willmigrate within the lens to reestablish equilibrium. This in turn cancause a change in the shape of the lens. This change in shape causesfurther changes in the optical properties of the lens. Whether a changein shape occurs depends, in part, on the flexibility of the lens, whichin turn depends in part on the T_(g) of the polymer used to form thefirst polymer matrix or due to the plasticization of the FPM by a mediumor a plasticizer or MC. If the polymer has a low T_(g), then the lenswill be flexible and a more pronounced shape change will occur. If thepolymer has a high T_(g), then the lens will be less flexible and lessshape change will occur. When no shape change occurs, the change inoptical properties will occur strictly based on the change in refractiveindex caused by the localized polymerization of the MC. The changesoccur in specific regions within the lens allowing for the creation ofcustomized lenses, including multifocal lenses.

[0052] In a preferred embodiment, the MC with a photopolymerizable groupis associated with a polymerization initiator which responds toultraviolet light. In this case, the lens blank is exposed toultraviolet light in a pattern to achieve the desired changes in opticalproperties of the lens.

[0053] The lenses of the invention are preferably formed by forming thefirst polymer matrix in a predetermined form in the presence of the MC.In this embodiment, the starting materials for the first polymer matrixand the MC as well as any necessary adjuvants and catalysts orinitiators are combined in a mold in the shape of the desired lens orelement. The first polymer matrix is then formed by polymerizing thestarting materials. As discussed above, the mechanism used to polymerizethe starting material must be such that it does not cause significantpolymerization of the MC. While some polymerization of the MC may occur,it should not deplete the amount of free MC in the lens to a level whereno change of optical properties can be accomplished through thepolymerization of the remaining MC. For this reason, the mechanism usedto polymerized the starting materials for the first polymer matrixshould be different that that used to polymerize the MC or thepolymerization rate for the starting materials should be significantlygreater for the starting materials than for the MC.

[0054] Polymerization of the starting materials continues until thesupply of starting materials is exhausted or the first polymer matrix issuch that it forms a self-contained, self supporting structure. Byforming the matrix in the presence of the MC, the MC becomes dispersedwithin the matrix. The lens is then removed from the mold and is readyfor further customization. This is accomplished by exposing the lens toexternal stimuli as described above.

[0055] The following is an example of a method that can be used to formthe adjustable lenses useful in the practice of the invention. Siliconebased first polymer matrix starting materials comprising a vinylendcapped silicone macromers and hydroxyl endcapped organosiliconcompounds are combined in a mold with a silicone based MC such as thosedescribed above. A photoinitiator and a catalyst are also added to thecomposition as well as any required adjuvants such as UV absorbers andthe like. Upon addition of the catalyst, the silicone based startingmaterials polymerize to form the first polymer matrix leaving the MC,photoinitiator and other components unaffected and dispersed within thematrix. The MC can then be exposed to a suitable light source andpolymerized causing he desired change in optical properties.

[0056] In an alternative embodiment, an aqueous solution of highmolecular weight (>10,000) derivatized PVA (dPVA) with reactivemethacrylate side groups and low molecular weight (˜1,000) dPVA withreactive acrylate side groups and a photoinitiator is place in a mold.The low molecular weight dPVA is the MC in this embodiment. The solutionis than exposed to ultraviolet light such that the high molecular weightdPVA polymerizes to form the first polymer matrix. While some of the lowmolecular weight dPVA may also polymerize, a significant portion remainsunpolymerized when the matrix is formed along with some of the freemethacrylate groups on the high DPVA may remain free. This unpolymerizedlow molecular weight dPVA is the free to be polymerized at a later time,thereby causing changes in the optical properties of the lens. In asimilar manner, PHEMA abased system can be used where the high molecularweight component has reactive methacrylate groups and the low molecularweight components contain acrylate based groups.

[0057] The methods for forming the lenses are illustrative of thetechniques that may be used in the practice of the invention. Othermethods for forming lenses useful in the practice of the invention areknow to those skilled in the art.

[0058] The method of the invention can be used to dispense ophthalmiclenses which include corrective spectacles and contact lenses. In thisembodiment, the user of the lens is first examined to determine theoptical requirements for the lenses. This is done through standardophthalmologic examination methods such as visual acuity testing, andthe like.

[0059] Once the optical requirements of the lens are determined, a lensis selected and then exposed to an external stimulus in a pattern and atan intensity so as to produce the desired changes in optical properties.For example, for a patient with hyperopia, the central portion of thelens is exposed to the stimulus or a profiled beam that causespolymerization to occur at a desired depth wise and site specific. Inthe case of myopia, the outer edges of the lens are exposed or aprofiled beam that causes polymerization to occur at a desired depthwise and site specific. Presbyopia can be corrected by exposing the lensin a pattern of concentric rings, thereby creating a multifocal lens.Astigmatism can also be corrected through the use of the appropriatepattern along a certain meridian.

[0060] In one embodiment, the customization of the lenses isaccomplished at a central facility or distribution point. In thisembodiment, the lens requirements are transmitted to the distributionpoint, a set of lenses is selected, and each lens is separately exposedto an external stimulus to produce the desired changes in opticalproperties and the distribution facility then sends the customizedlenses to the dispensing location.

[0061] In an alternative embodiment, the lenses are customized at thedispensing location. In this instance, once the desired lens propertieshave been determined, a lens is then modified in the manner describedabove to create a customized lens that meets the requirements of thepatient. This second embodiment allows for more precise customization ofthe lens. In the case of corrective lenses or contact lenses, it ispossible to prepare a customized lens, allow the patient to wear thelens, evaluate the vision correction with the lens and, if necessary,further change the optical properties to optimize the correction of thelenses.

EXAMPLE 1

[0062] Materials comprising various amounts of (a) poly-dimethylsiloxaneendcapped with 10 diacetoxymethylsilane (“PDMS”) (36000 g/mol), (b)dimethylsiloxane-diphenylsiloxane copolymer endcapped withvinyl-dimethyl silane (“DMDPS”) (15,500 g/mol), and (c) aUV-photoinitiator, 2,2-dimethoxy-2-phenylacetophenone (“DMPA”) as shownby Table 1 were made and tested. PDMS is the monomer which forms firstpolymer matrix, and DMDPS and DMPA together comprise the refractionmodulating composition. TABLE 1 PDMS (wt. %) DMDPS (wt. %) DMPA (wt. %)a1 90 10 1.5 2 80 20 1.5 3 75 25 1.5 4 70 30 1.5

[0063] Briefly, appropriate amounts of PMDS (Gelest DMS-D33; 36000g/mol), DMDPS (Gelest PDV-0325; 3.0-3.5 mole % diphenyl, 15,500 g/mol),and DMPA (Acros; 1.5 wt % with respect to DMDPS) were weighed togetherin an aluminum pan, manually mixed at room temperature until the DMPAdissolved, and degassed under pressure (5 mtorr) for 2-4 minutes toremove air bubbles. Photosensitive prisms were fabricated by pouring theresulting silicone composition into a mold made of three glass slidesheld together by scotch tape in the form of a prism and sealed at oneend with silicone caulk. The prisms are ˜5 cm long and the dimensions ofthe three sides are ˜8 mm each. The PDMS in the prisms was moisturecured and stored in the dark at room temperature for a period of 7 daysto ensure that the resulting first polymer matrix was non-tacky, clear,and transparent.

[0064] The amount of photo initiator (1.5 wt. %) was based on priorexperiments with fixed MC monomer content of 25% in which thephotoinitiator content was varied. Maximal refractive index modulationwas observed for compositions containing 1.5% and 2 wt. % photoinitiatorwhile saturation in refractive index occurred at 5 wt. %.

EXAMPLE 2

[0065] Synthesis MC Monomers

[0066] As illustrated by Scheme 1, commercially available cyclicdimethylsiloxane tetramer (“D₄”), cyclic methylphenylsiloxane trimer(“D₃′”) in various ratios were ring-opened by 15 triflic acid andbis-methacryloxylpropyltetramethyldisiloxane (“MPS”) were reacted in aone pot synthesis. U.S. Pat. No. 4,260,725; Kunzler, J. F., Trends inPolymer Science, 4: 52-59 (1996); Kunzler et al. J. Appl. Poly. Sci.,55: 611-619 (1995); and Lai et al., J. Poly. Sci. A. Poly. Chem.,33:1773-1782 (1995).

[0067] RMC Monomer

[0068] Briefly, appropriate amounts of MPS, D₄, and D₃′ were stirred ina vial for 1.5-2 hours. An appropriate amount of triflic acid was addedand the resulting mixture was stirred for another 20 hours at roomtemperature. The reaction mixture was diluted with hexane, neutralized(the acid) by the addition of sodium bicarbonate, and dried by theaddition of anhydrous sodium sulfate. After filtration androtovaporation of hexane, the MC monomer was purified by furtherfiltration through an activated carbon column. The MC monomer was driedat 5 mtorr of pressure between 70-80 ° C. for 12-18 hours.

[0069] The amounts of phenyl, methyl, and endgroup incorporation werecalculated from ¹H-NMR spectra that were run in deuterated chloroformwithout internal standard tetramethylsilane (“TMS”). Illustrativeexamples of chemical shifts for some of the synthesized MC monomersfollows. A 1000 g/mole MC monomer containing 5.58 mole % phenyl (made byreacting: 4.85 g (12.5 mmole) of MPS; 1.68 g (4.1 mmole) of D₃′; 5.98 g(20.2 mmole) of D₄; and 110 μl (1.21 mmole) of triflic acid: δ=7.56-7.57ppm (m, 2H) aromatic, δ=7.32-7.33 ppm (m, 3H) aromatic, δ=6.09 ppm (d,2H) olefinic, δ=5.53 ppm (d, 2H) olefinic, δ=4.07-4.10 ppm (t, 4H)—O—CH₂ CH₂CH₂—, δ=1.93 ppm (s, 6H) methyl of methacrylate, δ=1.65-1.71ppm (m, 4H) —CH₂CH₂ CH₂—, δ=0.54-0.58 ppm (m, 4H) —O—CH₂CH₂CH₂ —Si,δ=0.29-0.30 ppm (d, 3H), CH₃ —Si-Phenyl, δ0.04-0.08 ppm (s, 50 H) (CH₃)₂Si of the backbone.

[0070] A 2000 g/mole MC monomer containing 5.26 mole % phenyl (made byreacting: 2.32 g (6.0 mmole) of MPS; 1.94 g (4.7 mmole) of D₃′; 7.74 g(26.1 mmole) of D₄ and 140 μl (1.54 mmole) of triflic acid: δ=7.54-7.58ppm (m, 4H) aromatic, δ=7.32-7.34 ppm (m, 6H) aromatic, δ=6.09 ppm (d,2H) olefinic, δ=5.53 ppm (d, 2H) olefinic, δ=4.08-4.11 ppm (t, 4H)—O—CH₂ CH₂CH₂—, δ=1.94 ppm (s, 6H) methyl of methacrylate, δ=1.67-1.71ppm (m, 4H) —O—CH₂CH₂ CH₂—, δ=0.54-0.59 ppm (m, 4H) —O—CH₂CH₂CH₂ —Si,δ=0.29-0.31 ppm (m, 6H), CH₃ —Si—Phenyl, δ=0.04-0.09 ppm (s, 112H) (CH₃)₂ Si of the backbone.

[0071] A 4000 g/mole MC monomer containing 4.16 mole % phenyl (made byreacting: 1.06 g (2.74 mmole) of MPS; 1.67 g (4.1 mmole) of D₃′; 9.28 g(31.3 mmole) of D₄ and 160 μl (1.77 mmole) of triflic acid: δ=7.57-7.60ppm (m, 8H) aromatic, δ=7.32-7.34 ppm (m,12H) aromatic, δ=6.10 ppm (d,2H) olefinic, δ=5.54 ppm (d, 2H) olefinic, δ=4.08-4.12 ppm (t, 4H)—O—CH₂ CH₂CH₂—, δ=1.94 ppm (s, 6H) methyl of methacrylate, δ=1.65-1.74ppm (m, 4H) —O—CH₂CH₂ CH₂—, ≢=0.55-0.59 ppm (m, 4H) —O—CH₂CH₂CH₂ —Si,δ=0.31 ppm (m, 11H), CH₃ —Si—Phenyl, δ=0.07-0.09 ppm (s, 272 H) (CH₃ )₂Si of the backbone.

[0072] Similarly, to synthesize dimethylsiloxane polymer without anymethylphenylsiloxane units and endcapped with methyacryloxypropyldimethylsilane, the ratio of D₄ to MPS was varied without incorporatingD′₃ .

[0073] Molecular weights were calculated by ¹H-NMR and by gel permeationchromatography (“GPC”). Absolute molecular weights were obtained byuniversal calibration method using polystyrene and poly(methylmethacrylate) standards. Table 2 shows the characterization of other MCmonomers synthesized by the triflic acid ring opening polymerization.TABLE 2 Mole % Mole % Mole % Mn Mn Phenyl Methyl Methacrylate (NMR)(GPC) A 6.17 87.5 6.32 1001 946 1.44061 B 3.04 90.8 6.16 985 716 1.43188C 5.26 92.1 2.62 1906 1880 — D 4.16 94.8 1.06 4054 4200 1.42427 E 094.17 5.83 987 1020 1.42272 F 0 98.88 1.12 3661 4300 1.40843

[0074] At 10-40 wt %, these MC monomers of molecular weights 1000 to4000 g/mol with 3-6.2 mole % phenyl content are completely miscible,biocompatible, and form optically clear prisms and lenses whenincorporated in the silicone matrix. MC monomers with high phenylcontent (4-6 mole %) and low molecular weight (1000-4000 g/mol) resultedin increases in refractive index change of 2.5 times and increases inspeeds of diffusion of 3.5 to 5.0 times compared to the MC monomer usedin Table 1 (dimethylsiloxane-diphenylsiloxane copolymer endcapped withvinyldimethyl silane (“DMDPS”) (3-3.5 mole % diphenyl content, 15500g/mol). These MC monomers were used to make optical elements comprising:(a) poly-dimethylsiloxane endcapped with diacetoxymethylsilane (“PDMS”)(36000 g/mol), (b) dimethylsiloxane methylphenylsiloxane copolymer thatis endcapped with a methacryloxylpropyldimethylsilane group, and (c)2,2-dimethoxy-2-phenylacetophenone (“DMPA”). Note that component (a) isthe monomer that forms the first polymer matrix and components (b) and(e) comprise the refraction modulating composition.

EXAMPLE 3

[0075] Fabrication of Intraocular Lenses (“IOL”)

[0076] An intraocular mold was designed according to well-acceptedstandards. See e.g., U.S. Pat. Nos. 5,762,836; 5,141,678; and 5,213,825.Briefly, the mold is built around two plano-concave surfaces possessingradii of curvatures of −6.46 mm and/or −12.92 mm, respectively. Theresulting lenses are 6.35 mm in diameter and possess a thickness rangingfrom 0.64 mm, 0.98 mm, or 1.32 mm depending upon the combination ofconcave lens surfaces used. Using two different radii of curvatures intheir three possible combinations and assuming a nominal refractiveindex of 1.404 for the IOL composition, lenses with pre-irradiationpowers of 10.51 D (62.09 D in air), 15.75 D (92.44 in air), and 20.95 D(121.46 D in air) were fabricated.

FUTURE EXAMPLE 3A (CONTACT LENS) EXAMPLE 4

[0077] Stability of Compositions Against Leaching

[0078] Three IOLs were fabricated with 30 and 10 wt % of MC monomers Band D incorporated in 60 wt % of the PDMS matrix. After moisture curingof PDMS to form the first polymer matrix, the presence of any free MCmonomer in the aqueous solution was analyzed as follows. Two out ofthree lenses were irradiated three times for a period of 2 minutes using340 nm light, while the third was not irradiated at all. One of theirradiated lenses was then locked by exposing the entire lens matrix toradiation. All three lenses were mechanically shaken for 3 days in 1.0 MNaCl solution. The NaCl solutions were then extracted by hexane andanalyzed by ¹H-NMR. No peaks due to the MC monomer were observed in theNMR spectrum. These results suggest that the MC monomers did not leachout of the matrix into the aqueous phase in all three cases. Earlierstudies on a vinyl endcapped silicone MC monomer showed similar resultseven after being stored in 1.0 M NaCl solution for more than one year.

EXAMPLE 5

[0079] Toxicological Studies in Rabbit Eyes

[0080] Sterilized, unirradiated and irradiated silicone IOLs (fabricatedas described in Example 3) of the present invention and a sterilizedcommercially available silicone IOL were implanted in albino rabbiteyes. After clinically following the eyes for one week, the rabbits weresacrificed. The extracted eyes were enucleated, placed in formalin andstudied histopathologically. There is no evidence of corneal toxicity,anterior segment inflammation, or other signs of lens toxicity.

EXAMPLE 6

[0081] Irradiation of Silicone Prisms

[0082] Because of the ease of measuring refractive index change (n) andpercent net refractive index change (% n) of prisms, the inventiveformulations were molded into prisms for irradiation andcharacterization. Prisms were fabricated by mixing and pouring (a) 90-60wt % of high M_(n) PDMS, (b) 10-40 wt % of MC monomers in Table 2, and(c) 0.75 wt % (with respect to the MC monomers) of the photoinitiatorDMPA into glass molds in the form of prisms 5 cm long and 8.0 mm on eachside. The silicone composition in the prisms was moisture cured andstored in the dark at room temperature for a period of 7 days to ensurethat the final matrix was non-tacky, clear and transparent.

[0083] Two of the long sides of each prism were covered by a blackbackground while the third was covered by a photomask made of analuminum plate with rectangular windows (2.5 mm×10 mm). Each prism wasexposed to a flux of 3.4 mW/cm² of a collimated 340 nm light (peakabsorption of the photoinitiator) from a 1000 W Xe:Hg arc lamp forvarious time periods. The ANSI guidelines indicate that the maximumpermissible exposure (“MPE”) at the retina using 340 nm light for a10-30000 s exposure is 1000 mJ/cm². Criteria for Exposure of Eye andSkin. American National Standard Z136.1: 31-42 (1993). The single doseintensity 3.4 mW/cm² of 340 nm light for a period of 2 minutescorresponds to 408 mJ/cm² which is well within the ANSI guidelines. FIG.2 is an illustration of the prism irradiation procedure.

[0084] The prisms were subject to both (i) continuousirradiation—one-time exposure for a known time period, and (ii)“staccato” irradiation—three shorter exposures with long intervalsbetween them. During continuous irradiation, the refractive indexcontrast is dependent on the cross-linking density and the mole % phenylgroups, while in the interrupted irradiation, MC monomer diffusion andfurther cross-linking also play an important role. During staccatoirradiation, the MC monomer polymerization depends on the rate ofpropagation during each exposure and the extent of interdiffusion offree MC monomer during the intervals between exposures. Typical valuesfor the diffusion coefficient of oligomers (similar to the 1000 g/moleMC monomers used in the practice of the present invention) in a siliconematrix are on the order of 10⁻⁶ to 10⁻⁷ cm²/s. In other words, theinventive MC monomers require approximately 2.8 to 28 hours to diffuse 1mm (roughly the half width of the irradiated bands). The distance of atypical optical zone in an IOL is about 4 to about 5 mm across. However,the distance of the optical zone may also be outside of this range.After the appropriate exposures, the prisms were irradiated without thephotomask (thus exposing the entire matrix) for 6 minutes using a mediumpressure mercury-arc lamp. This polymerized the remaining silicone MCmonomers and thus “locked” the refractive index of the prism in place.Notably, the combined total irradiation of the localized exposures andthe “lock-in” exposure was still within ANSI guidelines.

EXAMPLE 7

[0085] Prism Dose Response Curves

[0086] Inventive prisms fabricated from MC monomers described by Table 2were masked and initially exposed for 0.5, 1, 2, 5, and 10 minutes using3.4 mW/cm² of the 340 nm line from a 1000 W Xe:Hg arc lamp. The exposedregions of the prisms were marked, the mask detached and the refractiveindex changes measured. The refractive index modulation of the prismswas measured by observing the deflection of a sheet of laser lightpassed through the prism. The difference in deflection of the beampassing through the exposed and unexposed regions was used to quantifythe refractive index change (Δn) and the percentage change in therefractive index (% Δn).

[0087] After three hours, the prisms were remasked with the windowsoverlapping with the previously exposed regions and irradiated for asecond time for 0.5, 1, 2, and 5 minutes (total time thus equaled 1, 2,4, and 10 minutes respectively). The masks were detached and therefractive index changes measured. After another three hours, the prismswere exposed a third time for 0.5, 1, and 2 minutes (total time thusequaled 1.5, 3, and 6 minutes) and the refractive index changes weremeasured. As expected, the % Δn increased with exposure time for eachprism after each exposure resulting in prototypical dose responsecurves, Based upon these results, adequate MC monomer diffusion appearsto occur in about 3 hours for 1000 g/mole MC monomer.

[0088] All of the MC monomers (B—F) except for MC monomer A resulted inoptically clear and transparent prisms before and after their respectiveexposures. For example, the largest % n for MC monomers B, C, and D at40 wt % incorporation into 60 wt % FPMC were 0.52%, 0.63% and 0.30%respectively which corresponded to 6 minutes of total exposure (threeexposures of 2 minutes each separated by 3 hour intervals for MC monomerB and 3 days for MC monomers C and D). However, although it produced thelargest change in refractive index (0.95%), the prism fabricated from MCmonomer A (also at 40 wt % incorporation into 60 wt % FPMC and 6 minutesof total exposure—three exposures of 2 minutes each separated by 3 hourintervals) turned somewhat cloudy. Thus, if MC monomer A were used tofabricate an IOL, then the MC must include less than 40 wt % of MCmonomer A or the % Δn must be kept below the point where the opticalclarity of the material is compromised.

[0089] A comparison between the continuous and staccato irradiation forMC A and C in the prisms shows that lower % Δn values occurs in prismsexposed to continuous irradiation as compared to those observed usingstaccato irradiations. As indicated by these results, the time intervalbetween exposures (which is related to the amount of MC diffusion fromthe unexposed to exposed regions) may be exploited to precisely modulatethe refractive index of any material made from the inventive polymercompositions.

[0090] Exposure of the entire, previously irradiated prisms to a mediumpressure Hg arc lamp polymerized any remaining free MC. effectivelylocking the refractive index contrast. Measurement of the refractiveindex change before and after photolocking indicated no furthermodulation in the refractive index.

EXAMPLE 8

[0091] Optical Characterization of IOLs

[0092] Talbot interferometry and the Ronchi test were used toqualitatively and quantitatively measure any primary optical aberrations(primary spherical, coma, astigmatism, field curvature, and distortion)present in pre- and post-irradiated lenses as well as quantifyingchanges in power upon photopolymerization.

[0093] In Talbot interferometry, the test IOL is positioned between thetwo Ronchi rulings with the second grating placed outside the focus ofthe IOL and rotated at a known angle θ, with respect to the firstgrating.

[0094] Superposition of the autoimage of the first Ronchi ruling (p₁=300lines/inch) onto the second grating (P₂=150 lines/inch) produces moiréfringes inclined at an angle, α₁. A second moiré fringe pattern isconstructed by axial displacement of the second Ronchi ruling along theoptic axis a known distance, d, from the test lens. Displacement of thesecond grating allows the autoimage of the first Ronchi ruling toincrease in magnification causing the observed moiré fringe pattern torotate to a new angle, α₂. Knowledge of moiré pitch angles permitsdetermination of the focal length of the lens (or inversely its power)through the expression:$f = {\frac{p_{1}}{p_{2}}{d\left( {\frac{1}{{\tan \quad \alpha_{2}\sin \quad \theta} + {\cos \quad \theta}} - \frac{1}{{\tan \quad \alpha_{1}\sin \quad \theta} + {\cos \quad \theta}}} \right)}^{- 1}}$

[0095] To illustrate the applicability of Talbot interferometry to thiswork, moiré fringe patterns of one of the inventive, pre-irradiated IOLs(60 wt % PDMS, 30 wt % MC monomer B, 10 wt % MC monomer D, and 0.75%DMPA relative to the two MC monomers) measured in air is presented inFIG. 3. Each of the moiré fringes was fitted with a least squaresfitting algorithm specifically designed for the processing of moirépatterns. The angle between the two Ronchi rulings was set at 12°, thedisplacement between the second Ronchi ruling between the first andsecond moiré fringe patterns was 4.92 mm, and the pitch angles of themoiré fringes, measured relative to an orthogonal coordinate systemdefined by the optic axis of the instrument and crossing the two Ronchirulings at 90, were α₁=−33.2±0.30 and α₂=−52.7±0.40. Substitution ofthese values into the above equation results in a focal length of10.71±0.50 mm (power=93.77±4.6 D).

[0096] Optical aberrations of the inventive IOLs (from eitherfabrication or from the stimulus-induced polymerization of the MCcomponents) were monitored using the “Ronchi Test” which involvesremoving the second Ronchi ruling from the Talbot interferometer andobserving the magnified autoimage of the first Ronchi ruling afterpassage though the test IOL. The aberrations of the test lens manifestthemselves by the geometric distortion of the fringe system (produced bythe Ronchi ruling) when viewed in the image plane. A knowledge of thedistorted image reveals the aberration of the lens. In general, theinventive fabricated lenses (both pre and post irradiation treatments)exhibited sharp, parallel, periodic spacing of the interference fringesindicating an absence of the majority of primary-order opticalaberrations, high optical surface quality, homogeneity of n in the bulk,and constant lens power. FIG. 4 is an illustrative example of aRonchigram of an inventive, pre-irradiated IOL that was fabricated from60 wt % PDMS, 30 wt % MC monomer B, 10 wt % MC monomer D, and 0.75% ofDMPA relative to the 2 MC monomers.

[0097] The use of a single Ronchi ruling may also be used to measure thedegree of convergence of a refracted wavefront (i.e., the power). Inthis measurement, the test IOL is placed in contact with the firstRonchi ruling, collimated light is brought incident upon the Ronchiruling, and the lens and the magnified autoimage is projected onto anobservation screen. Magnification of the autoimage enables measurementof the curvature of the refracted wavefront by measuring the spatialfrequency of the projected fringe pattern. These statements arequantified by the following equation:$P_{r} = {\frac{1000}{L}\left( {1 + \frac{d_{s}}{d}} \right)}$

[0098] wherein P_(v) is the power of the lens expressed in diopters, Lis the distance from the lens to the observing plane, d_(s), is themagnified fringe spacing of the first Ronchi ruling, and d is theoriginal grating spacing.

EXAMPLE 9

[0099] Power Changes From Photopolymerization of the Inventive IOLs

[0100] An inventive IOL was fabricated as described by Example 3comprising 60 wt % PDMS (n_(D)=1.404), 30 wt % of MC monomer B(n_(D)=1.4319), 10 wt % of MC monomer D (n_(D)=1.4243), and 0.75 wt % ofthe photoinitiator DMPA relative to the combined weight percents of thetwo MC monomers. The IOL was fitted with a 1 mm diameter photomask andexposed to 3.4 mW/cm² of 340 nm collimated light from a 1000 W Xe:Hg arclamp for two minutes. The irradiated lens was then placed in the darkfor three hours to permit polymerization and MC monomer diffusion. TheIOL was photolocked by continuously exposing the entire lens for sixminutes using the aforementioned light conditions. Measurement of themoiré pitch angles followed by substitution into equation 1 resulted ina power of 95.1±2.9 D (f=10.52 ±0.32 mm) and 104.1±3.6 D (f=9.61 mm±0.32mm) for the unirradiated and irradiated zones, respectively.

[0101] The magnitude of the power increase was more than what waspredicted from the prism experiments where a 0.6% increase in therefractive index was routinely achieved. If a similar increase in therefractive index was achieved in the IOL, then the expected change inthe refractive index would be 1.4144 to 1.4229. Using the new refractiveindex (1.4229) in the calculation of the lens power (in air) andassuming the dimensions of the lens did not change uponphotopolymerization, a lens power of 96.71 D (f=10.34 mm) wascalculated. Since this value is less than the observed power of104.1±3.6 D, the additional increase in power must be from anothermechanism.

[0102] Further study of the photopolymerized IOL showed that subsequentMC monomer diffusion after the initial radiation exposure leads tochanges in the radius of curvature of the lens. See e.g., FIG. 5. The MCmonomer migration from the unradiated zone into the radiated zone causeseither or both of anterior and posterior surfaces of the lens to swellthus changing the radius of curvature of the lens. It has beendetermined that a 7% decrease in the radius of curvature for bothsurfaces is sufficient to explain the observed increase in lens power.

[0103] The concomitant change in the radius of curvature was furtherstudied. An identical IOL described above was fabricated. A Ronchiinterferogram of the IOL is shown in FIG. 6a (left interferogram). Usinga Talbot interferometer, the focal length of the lens was experimentallydetermined to be 10.52±0.30 mm (95.1 D±2.8 D). The IOL was then fittedwith a 1 mm photomask and irradiated with 3.4 mW/cm² of 340 nmcollimated light from a 1000 W Xe:Hg arc lamp continuously for 2.5minutes. Unlike the previous IOL, this lens was not “locked in” threehours after irradiation. FIG. 6b (right interferogram) is the Ronchiinterferogram of the lens taken six days after irradiation. The mostobvious feature between the two interference patterns is the dramaticincrease in the fringe spacing, which is indicative of an increase inthe refractive power of the lens.

[0104] Measurement of the fringe spacings indicates an increase ofapproximately +38 diopters in air (f≈7.5 mm). This corresponds to achange in the order of approximately +8.6 diopters in the eye. Sincemost post-operative corrections from cataract surgery are within 2diopters, this experiment indicates that the use of the inventive IOLswill permit a relatively large therapeutic window.

EXAMPLE 10

[0105] Photopolymerization Studies of Non-Phenyl-Containing IOLs

[0106] Inventive IOLs containing non-phenyl containing MC monomers werefabricated to further study the swelling from the formation of thesecond polymer matrix. An illustrative example of such an IOL wasfabricated from 60 wt % PDMS, 30 wt % MC monomer E, 10 wt % MC monomerF, and 0.75% DMPA relative to the two MC monomers. The pre-irradiationfocal length of the resulting IOL was 10.76 mm (92.94±2.21 D).

[0107] In this experiment, the light source was a 325 nm laser line froma He:Cd laser. A 1 mm diameter photomask was placed over the lens andexposed to a collimated flux of 0.75 mW/cm² at 325 nm for a period oftwo minutes. The lens was then placed in the dark for three hours.Experimental measurements indicated that the focal length of the IOLchanged from 10.76 mm±0.25 mm (92.94 D±2.21 D) to 8.07 mm±0.74 mm(123.92 D±10.59 D) or a dioptric change of +30.98 D±10.82 D in air. Thiscorresponds to an approximate change of +6.68 D in the eye. The amountof irradiation required to induce these changes is only 0.09 J/cm², avalue well under the ANSI maximum permissible exposure (“MPE”) level of1.0 J/cm².

EXAMPLE 11

[0108] Monitoring for Potential IOL Changes from Ambient Light

[0109] The optical power and quality of the inventive IOLs weremonitored to show that handling and ambient light conditions do notproduce any unwanted changes in lens power. A 1 mm open diameterphotomask was placed over the central region of an inventive IOL(containing 60 wt % PDMS, 30 wt % MC monomer E, 10 wt % MC monomer F,and 0.75 wt % DMPA relative to the two MC monomers), exposed tocontinuous room light for a period of 96 hours, and the spatialfrequency of the Ronchi patterns as well as the moiré fringe angles weremonitored every 24 hours. Using the method of moiré fringes, the focallength measured in the air of the lens immediately after removal fromthe lens mold is 10.87±0.23 mm (92.00 D±1.98 D) and after 96 hours ofexposure to ambient room light is 10.74 mm±0.25 mm (93.11 D±2.22 D).Thus, within the experimental uncertainty of the measurement, it isshown that ambient light does not induce any unwanted change in power. Acomparison of the resulting Ronchi patterns showed no change in spatialfrequency or quality of the interference pattern, confirming thatexposure to room light does not affect the power or quality of theinventive IOLs.

EXAMPLE 12

[0110] Effect of the Lock in Procedure of an Irradiated IOL

[0111] An inventive IOL whose power had been modulated by irradiationwas tested to see if the lock-in procedure resulted in furthermodification of lens power. An IOL fabricated from 60 wt % PDMS, 30 wt %MC monomer E, 10 wt % MC monomer F, and 0.75% DMPA relative to the twoMC monomers was irradiated for two minutes with 0.75 mW/cm² of the 325nm laser line from a He:Cd laser and was exposed for eight minutes to amedium pressure Hg arc lamp. Comparisons of the Talbot images before andafter the lock in procedure showed that the lens power remainedunchanged. The sharp contrast of the interference fringes indicated thatthe optical quality of the inventive lens also remained unaffected.

[0112] To determine if the lock-procedure was complete, the IOL wasrefitted with a 1 mm diameter photomask and exposed a second time to0.75 mW/cm² of the 325 laser line for two minutes. As before, noobservable change in fringe space or in optical quality of the lens wasobserved.

EXAMPLE 13

[0113] Monitoring for Potential IOL Changes from the Lock-In

[0114] A situation may arise wherein the implanted IOL does not requirepost-operative power modification. In such cases, the IOL must be lockedin so that its characteristic will not be subject to change. Todetermine if the lock-in procedure induces undesired changes in therefractive power of a previously unirradiated IOL, the inventive IOL(containing 60 wt % PDMS, 30 wt % MC monomer E, 10 wt % MC monomer F,and 0.75 wt % DMPA relative to the two MC monomers) was subject to three2 minute irradiations over its entire area that was separated by a 3hour interval using 0.75 mW/cm² of the 325 laser line from a He:Cdlaser. Ronchigrams and moiré fringe patterns were taken prior to andafter each subsequent irradiation. The moiré fringe patterns taken ofthe inventive IOL in air immediately after removal from the lens moldand after the third 2 minute irradiation indicate a focal length of10.50 mm±0.39 mm (95.24 D±3.69 D) and 10.12 mm±0.39 mm (93.28 D±3.53D)respectively. These measurements indicate that photolocking a previouslyunexposed lens does not induce unwanted changes in power. In addition,no discernable change in fringe spacing or quality of the Ronchi fringeswas detected indicating that the refractive power had not changed due tothe lock-in.

[0115] In a third embodiment, the lenses are manufactured at a centralfacility and the initial customization is done at that location. Thelens is then sent to the dispensing location. The lens may be furthermodified at the dispensing location based on feedback from the patientafter use of the lens.

[0116] Although the present invention and its advantages have beendescribed in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the invention as defined by the appended claims.Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A method for preparing a customized lenscomprising the steps of: determining the optical requirements of thelens; exposing a self-contained lens to an external stimulus, therebycausing changes in the optical properties of said lens to match saidoptical requirements; wherein said lens contains a modifying compositioncapable of stimulus induced polymerization and change as achieved bysaid exposure to stimulus.
 2. The method of claim 1 wherein saidcustomizing step occurs in vivo.
 3. The method of claim 1 wherein saidcustomizing step occurs in vitro.
 4. The method of claim 1 wherein saidlens is a contact lens.
 5. The method of claim 1 wherein said lens is acorrective lens for glasses.
 6. The method of claim 1 wherein saidmodifying composition is photopolymerizable moiety.
 7. The method ofclaim 1 wherein said lens blank further comprises a first polymermatrix.
 8. The method of claim 1 wherein the step of determining theoptical requirements of the lens comprises conducting an ophthalmologicexamination of a patient.
 9. The method of claim 1 wherein said externalstimulus is light.
 10. The method of claim 1 wherein said light is UVlight.
 11. A method for preparing a customized lens comprising: a.conducting an examination to determine the optical properties requiredfor the lens; b. exposing a lens to an external stimulus to inducechanges in the optical properties of the lens to match the opticalproperties required for the lens; and
 12. The method of claim 11 whereinsaid lens comprises a modifying composition dispersed within the lens,the modifying composition capable of stimulus-induced polymerization.13. The method of claim 11 further comprising the step of re-exposingthe lens to external stimuli to induce further changes in the opticalproperties of the lens blank.
 14. The method of claim 11 wherein saidmodifying composition contains a photopolymerizable moiety.
 15. Themethod of claim 11 wherein said external stimulus is light.